Key Theories And Methods Of Cooperative Transportation Organization In Multimodal Transportation Network

With the continuous development of social economy,the transportation demand of different kinds of goods and different modes of transportation is increasing day by day,and collaborative organization of various modes of transportation is required to improve comprehensive transportation efficiency and achieve better social and economic benefits.In the process of multimodal transportation,reasonable choice of transportation modes and routes can give full play to the advantages of multimodal transportation,achieve deep integration of various transportation modes,and promote cost reduction and efficiency improvement,energy saving and carbon reduction.At present,the development of multimodal transport in China is still in the initial acceleration period,the proportion of multimodal transport in the total freight is still low.There are many problems in the cooperative transport organization of multimodal transport network that need further study.In the thesis,aiming at the key problems faced by multimodal cooperative transportation organization,it is of great theoretical and practical significance to study the mechanism of interaction among various influencing factors of multimodal transportation and the optimization and evaluation of transportation schemes,and to carry out theoretical and numerical analysis from the aspects of railway transportation subsidy mechanism,network optimization,network cooperative transportation organization optimization and scheme evaluation.The specific research content mainly includes the following aspects:(1)Analysis of influencing factors of collaborative transportation organization in multimodal transportation networkThe influence of hub node and transport arc on network modeling is analyzed from the perspective of composition of multimodal transport network To meet the requirements of shippers on transportation tasks and the diversified and personalized services provided by transportation enterprises,the cargo category,the time-space objectives and transportation quality of multimodal transport are analyzed in terms of the objectives of transportation task requirements.In the analysis of factors of multimodal transport scheme,the composition and expression of relevant parameters affecting transportation time and transportation cost are analyzed,and the current situation of the carbon emission right market and the calculation method of carbon emission are analyzed.(2)Modeling and optimization of subsidy mechanism for railway intermodal transportationIn view of the multimodal railway freight subsidy mechanism,this thesis takes the disordered competition between regions faced by China-Europe freight express due to different local government subsidy policies as a key issue to study.A two-level programming model of freight subsidy for China-Europe freight express is established by taking the disorderly competition problem faced by China-Europe freight express as the starting point.Among them,the upper model minimizes the transportation cost of departure and destination(OD),while the lower model maximizes the freight growth of China-Europe freight express through unit subsidies.The Pattern Search algorithm and Dijkstra algorithm are designed to solve the upper and lower models respectively,and the appropriate railway freight subsidy mechanism is obtained by analyzing the operation cases of China-Europe freight express in the Yangtze River Delta and surrounding areas.(3)Modeling and solving of multimodal transportation network optimizationTo solve the optimization problem of multimodal transportation network with both direct and non-direct modes under multitask,a multimodal transportation network optimization model with the objectives of time connection,scale economic benefit,total cost of transportation network and carbon emission of network is established,and a hyper-heuristic algorithm is designed.In the upper algorithm using genetic and simulated annealing algorithm as a high-level strategy,seven lower-level heuristic operators are designed from three aspects of local optimization,variation,destruction and reconstruction.12 cities along the Yangtze River economic belt are selected for example analysis.(4)Optimization of collaborative transportation organization in multimodal transportation networkIn the optimization of cooperative transportation organization of transportation network,the cold chain cargo transportation is studied as a key problem.Starting from the characteristics of certain kinds of cold chain goods,the thesis firstly takes the total transportation cost as a single objective,constructs the optimization model of railway cold chain logistics network based on freight subsidy,and designs the adaptive genetic-simulated annealing algorithm.Taking the cold chain transportation in the Yangtze River Delta-Chengdu-Chongqing region as an example,the optimal transportation scheme of cold chain transportation network is obtained.The sensitivity analysis of the impact of freight subsidy,train travel speed,soft time window and carbon tax rate factors on the total network cost and rail transport market is also conducted.On this basis,the multi-objective optimization problem under uncertain demand is studied in depth.Taking the total network cost,carbon emission and cargo loss rate as the optimization objectives,a multi-objective chance-constrained programming model is established,and an adaptive genetic-simulated annealing algorithm is designed to solve the freight transportation case study of the Yangtze River Delta-Chengdu-Chongqing region.Sensitivity analysis is carried out for freight subsidy,train travel speed and cold chain cargo category.(5)Evaluation method of collaborative transportation organization scheme of multimodal transportation networkThe comprehensive evaluation index system of multimodal transportation scheme is established from the level of shipper,transportation enterprise and government according to the hierarchical analysis method.Qualitative indexes are quantitatively determined by using triangular fuzzy number method.The weight of each index is determined after the quantitative indexes and qualitative indexes are normalized by the entropy weight method.Finally,the weighted comprehensive evaluation matrix is positively evaluated by using TOPSIS method.By calculating the distance and relative closeness of negative ideal solution,the overall ranking of comprehensive evaluation for various transportation schemes is obtained.By carrying out research on key theoretical framework and system evaluation index system of multimodal network collaborative transportation organization,establishing optimization method of multimodal transportation organization based on mathematical optimization model can enrich relevant theories of multimodal network collaborative organization optimization,which has great theoretical and practical significance for guiding multimodal transport organization mode.